This manmade debris permeates our bodies and our planet, but what's the harm?
The environment is something that many people take personally, and environmental issues can often result in emotional responses — often perfectly warranted ones. Compounding that is the plastics industry, often seen as corrupt bad guys who pursue every last penny no matter the cost to the planet. And compounding that even further is the question of public health: with environmental microplastics filling our lungs and our bodies, what's to become of us? Put it all together and you've got an explosive issue, with something in it to outrage just about everyone. But today we're going to make an effort, Quixotic or not, to push the emotion aside and look at just the science of environmental microplastics.
As always, we'll begin with a definition and description of what microplastics are. Strictly speaking, they're any pieces of plastic smaller than 5mm, often described as the size of a grain of rice. This can be either a piece of plastic that was originally that small, or it can be a bit of debris from something that was larger and broke down. These two types represent the two main categories of microplastics: primary microplastics and secondary microplastics.
A primary microplastic is an item manufactured to be that small. Common examples are nurdles, which are pellets of raw material intended to be melted down and used in industry to mold something larger; and microbeads, which are microscopic pellets often added to cosmetics and toothpaste, and used either as emulsifiers, fillers, or abrasive grit. A secondary microplastic is a bit of something larger that degraded. Many plastics break down quite rapidly outdoors, with ultraviolet radiation being one antagonist and movement (such as wave action in the ocean) being another. All of the plastic you might find in the ocean gyres would be these secondary microplastic particulates, since it takes an object over a year to circulate out that far. For a much deeper dive on this (no pun intended), see Skeptoid episodes #132 on the Pacific Garbage Patch and #665 on ocean plastics.
We've already got a whole generation of people who were born, grew up and lived their entire lives, and died, in a world filled with microplastics — and not one person has ever shown any detrimental effect; at least, not that's ever been identified as such. In researching this episode, I read the abstracts of scores of scientific papers to get the lay of the land. Three things are very clear:
It's the same in articles that look at microplastics in the environment and in animals, both on the land and in the oceans. Microplastics are everywhere in all of those environments, and just like how you and I eat and breathe them every day, so do the animals. So do the fish. Just as much published research is out there proving that the microplastics have already gotten everywhere and are found throughout the bodies of animals just as they are throughout the bodies of humans. There is no doubt about that. Microplastics already permeate everything. They permeate our bodies, they permeate animals' bodies, and we keep finding them in unexpected places in the environment. It's all factual and absolutely true.
Now for a moment here, I'm going to step away from summarizing what's in the published research, and do something I shouldn't really do: speak purely from the position of my own personal notion of common sense. I give that disclaimer because it's important. You should, accordingly, give less weight to it. Stuff in the environment permeating everything is the way the whole world has always worked. This is why we can get such great science from ice cores from 100,000 years ago; we can tell what pollutants were in the atmosphere from forest fires and volcanoes. Trees give us a detailed chemical record of what pollutants and weather they were exposed to. Tooth enamel from people and animals who died hundreds of thousands of years ago tells us what they ate. We know about the asteroid that killed the dinosaurs from the elements in a stratum of rock. Speleothems in caves tell us about the ancient climate and contaminants in the atmosphere. Even the dirt in Washington has dirt from Canada mixed in, from floods 15,000 years ago. The Earth is one big gigantic entropy machine, and stuff gets everywhere. As we've observed more than once here on Skeptoid, you probably have about 180 billion atoms of plutonium in your body (a toxic substance), because you eat it with every bite of food, and you inhale it with every breath. It's because you live on Earth. The same goes for every fish, for every turtle, and for every plant.
This kind of entropy is not inherently good or bad. Some cases of it are bad, other cases (like pollination) are good. Most cases are at such incredibly low levels of dilution — like the plutonium in your body — that they have no consequences at all. It happens, and it's not inherently bad.
Some make the argument at this point "Yeah, but all of those things are natural, but plastic is artificial, and it's not natural to have artificial things in the environment." That's true, but it's not inherently harmful to have artificial debris in the environment, just as it's not inherently beneficial to have natural debris in the environment. Many times here on Skeptoid we've observed that plenty of natural compounds are horribly dangerous: salmonella, asbestos, fire, lightning, botulism, box jellyfish neurotoxin. Similarly humans make plenty of artificial things that are completely harmless: I can drop a glass marble into the Brazilian rainforest, and it's not going to cause any trouble whatsoever.
OK I'm now off my personal soapbox; let's turn back to what the published research says. There's one really popular and often-cited paper that gives a really good overview of the situation, published in 2016 in Environmental Science Europe, and titled "Microplastics in the aquatic and terrestrial environment: sources (with a specific focus on personal care products), fate and effects." It's freely available online and is a recommended read, but for brevity and clarity I'm going to give a few quotes from its abstract. One thing it points out echoes the findings of NOAA (National Oceanic and Atmospheric Administration) that there's still no clear evidence that microplastics are any more harmful to marine life than sand or the other things they eat which pass right through:
The same goes for chemical pollutants that many people believe microplastics are always leeching out into the environment and into animals which consume them (forgive the somewhat dense language here):
And finally, the article acknowledges (as they all do) that we still don't know a lot:
But nevertheless makes the conclusion that I think is a very sane one:
I see my job here at Skeptoid to show what the best science is on a given subject, and if it's actionable science — meaning, a finding that tells us how we can make or do something better, safer, or more efficiently — I'd advocate for that. In this case, I've found that the science is a lot less actionable that I would have expected. There's just not a whole lot we can do about this. First, we don't have clear evidence that microplastics are all that harmful — if you remember in the episode on ocean plastics, NOAA does not recommend any efforts to clean up plastic out in the ocean gyres, not only because it's impossible from an engineering standpoint, but more importantly, there's no clear benefit in doing so. We kind of have that same situation with the larger global microplastics issue. We're not reducing any clearly identified threat, and there's that entropy problem again: no matter what, it is impossible to stop the release of microplastics into the environment, just as it's impossible to stop dust from accumulating in your house. Entropy always wins. We can mitigate such problems, and we should, but there's always a point of diminishing returns; and on the subject of microplastics, I expect we'd hit that point much sooner than we expect.
So what we have is things like, in the United States, the Microbead-Free Waters Act of 2015, which became law in 2015 and prohibited the manufacture and sale of personal care products designed to be washed off, like toothpaste, containing primary microplastics. My read is that the more you learn about the relevant sciences, the less real-world impact a bill like this is likely to have. I think it's something of a feel-good law, like banning plastic trash bags as we talked about in episode #711, or banning plastic straws in episode #717. Nevertheless, the act's heart and its intent are in the right place; and it's the kind of industry regulation that incentivizes research into more sustainable alternatives, which is something all industry should always be thinking about. So, while I wouldn't have bent over backwards to pass this particular act, I still think it's better to have it in place than to not.
One thing I always point out on Skeptoid is that in order to devise an effective solution to a problem, you must have an accurate understanding of the problem. And, so often in environmental problems especially, the public's perception has been skewed by exaggerated and sensationalized descriptions that are well intended to raise awareness, but actually counterproductive in that they mischaracterize the facts. That's just what we observe with the issue of environmental microplastics. However, that we have no evidence of immediate or severe harm from microplastics should not be the end of the story, because it's just one piece of a much larger concern. And that's the question of what kind of stewards of our planet do we want to be. There is very little controversy over that question: we want this to be a nice place. We want to be the best stewards we can be, and we want to always do a little better. But given the science, microplastics probably shouldn't be anyone's top priority; global warming would be the first, and if the oceans are your jam then overfishing should be your second. But microplastics are still on the list — wherever you want them to be.
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